The natriuretic, diuretic, and vasorelaxant hormones atrial natriuretic factor (ANF) and brain natriuretic peptide (BNP) are synthesized and secreted mainly from the mammalian atria of the heart, and are crucial for the maintenance of cardiovascular homeostasis. Direct stimulation of isolated adult rat atrial tissue by stretch, endothelin-1, and phenylephrine was conducted to attempt to define the mechanisms invoked in controlling the secretion and gene expression of ANF and BNP in adult atrial cardiocytes. These stimuli represent models for mechanical, autocrine/paracine, and neuroendocrine stimulation of the endocrine heart. The expression of the early response genes c-fos, c-jun, Egr-1, and c-myc were also studied, since they may regulate ANF or BNP gene expression. Isolated rat atria were stimulated by stretch, endothelin-1, or phenylephrine. Radioimmunoassay was used to measure levels of ANF and BNP, and Northern blotting was employed to measure changes in mRNA levels. Stretch resulted in a rapid and short-lived increase in the secretion of ANF and BNP. Calculation of the ratio of ANF to BNP suggested that this may be due to exocytosis of granules that contain both peptides, as well as granules that contain ANF only. Stretch selectively stimulated the expression of the BNP, c-fos, Egr-1, and c-myc genes. Endothelin-1 stimulated the secretion of ANF and BNP, following a time course that is distinct from that elicited by stretch: the increase in secretion was gradual, reached a plateau, and after a few hours returns towards basal levels. The patterns was similar for ANF and BNP, which suggests that they are co-secreted in response to this stimulus. Phenylephrine stimulated ANF and BNP secretion, but their stimulated secretion was not co-regulated. Endothelin-1 and phenylephrine stimulated BNP, Egr-1, and c-myc gene expression. Phenylephrine also modestly stimulated ANF gene expression. Changes in ANF and BNP mRNA levels were not coordinated with increased BNP secretion. The results show that ANF and BNP secretion and gene expression are distinctly regulated; this may be due to the relative abundance of each hormone and to partially different mechanisms of secretion for each. Therefore, mechanical and neuroendocrine stimuli contribute in different and specific manners to the modulation of the endocrine heart and hence to the maintenance of cardiovascular homeostasis.

Although the cardiovascular changes associated with dynamic exercise have been investigated, there still remain many unanswered questions with respect to blood pressure following exercise. This study examined the effect of temperature on systolic (SBP), diastolic blood pressure (DBP), heart rate (HR), oxygen consumption $\rm(VO\sb2),$ and skin temperature (Tsk) in 10 healthy, young males (23-28 years of age), during a 60-minute supine post-exercise recovery period. On separate occasions, 20 minutes of treadmill exercise at heart rate of 140 beats per minute, preceded a 60-minute recovery period in a supine position conducted at either $\rm18\sp\circ C,\ 27\sp\circ C,\ or\ 40\sp\circ C.$ Results indicated that mean SBP was significantly more above baseline values at $\rm18\sp\circ C$ than at either $\rm27\sp\circ C\ or\ 40\sp\circ C.$ However, no significant difference in SBP was observed between recovery at $\rm27\sp\circ C\ and\ 40\sp\circ C.$ Also, no significant differences were observed among the three conditions for mean DBP. HR decreased progressively during recovery but remained above baseline values, except at $\rm18\sp\circ C$. No significant differences among recovery conditions were observed for $\rm VO\sb2.$ Mean skin temperatures were significantly different among the three recovery conditions except immediately upon entering the chamber. It was concluded that recovery at $\rm18\sp\circ C$ maintained post-exercise SBP above baseline values while $\rm27\sp\circ C\ and\ 40\sp\circ$C caused a decrease in post-exercise SBP with respect to baseline values. DBP and $\rm VO\sb2$ during recovery were not influenced by temperature. HR decreased gradually post-exercise with the lowest HR observed during cold exposure. Therefore, for the conditions of this experiment temperature had a significant effect on SBP, HR and skin temperature all of which effectively appeared to be associated with peripheral vasodilation/constriction mechanisms.

Recent studies have indicated the possible importance of cytokines in the onset of term and preterm labour. To understand this further, the effect of interleukin-1 ($\alpha$ and $\beta)$ and interleukin 6 on prostaglandin output by dispersed cells from human amnion, chorion laeve, and decidua obtained at term (38-42 weeks gestation) was examined. During the first or second 24 hours of culture, no significant effect of these interleukins on prostaglandin output was observed. The apparent refractoriness of these cells to interleukin-1 was further investigated by studying the distribution of IL-1 receptors in frozen sections of undisrupted fetal membranes and decidua at term. Whole-tissue and emulsion autoradiography indicated that receptors were present in the chorion and decidua but not in the amnion. Fresh cells labeled for IL-1 receptors confirmed the intact tissue findings. No labeling was found in the amnion; labeling was found in certain populations of the chorion cells. These studies indicate that under normal circumstances in human pregnancy at term, IL-1 does not stimulate prostaglandin production by dispersed cells. In the case of amnion, this may be due to the absence of receptors, and therefore it would appear that the IL-1 receptor must first be induced in this tissue before it can respond to this cytokine. Furthermore, although chorion laeve expresses the IL-1 receptor, dispersed cells from this tissue did not respond to the cytokine by increasing prostaglandin output. (Abstract shortened by UMI.)

The purpose of this investigation was to examine the role of water intake on post-exercise hyperthermia. Ten active, non-competitive male volunteers performed twenty minute treadmill exercise at equal relative intensities during two separate trials where: (1) gradual hypohydration took place, and (2) euhydration was induced by water ingestion in order to compensate for the body water volume loss demonstrated in the hypohydrated condition. Core temperature, represented by both esophageal and rectal temperatures, was recorded, along with surface temperatures (forearm, finger, chest thigh, and calf) and heart rate during a twenty-one minute adaptation period, throughout exercise and for forty minutes of recovery. Hematocrit samples were taken immediately prior to and following the exercise protocol and subject weights were measured before and after the testing session. The interaction between trials and time for esophageal and rectal temperatures and the difference between the hypohydration and euhydration trials for esophageal and rectal temperatures were all non-significant, and demonstrated that core temperature values did not differ between the hypohydrated and euhydrated conditions. However, core temperature was significantly different across time for both esophageal and rectal temperatures, due to a post-exercise elevated plateau from pre-exercise values. This elevation corresponded to the core temperature at which skin vessel dilation occurred during e exercise for both trials. The correlation between the difference in the hypohydration and euhydration esophageal elevations and the absolute and relative percentage weight loss of each subject after hypohydration further demonstrated a weak role for water intake in post-exercise hyperthermia. Several hypotheses are proposed to explain the post-exercise core temperature elevations in both the hypohydrated and euhydrated trials and the lack of significant difference between the two trials. (Abstract shortened by UMI.)

Reperfusion of an ischemic myocardium has been shown to cause increased injury to the post-ischemic myocardium. Studies exploring the mechanisms of ischemia/reperfusion (IR) injury are abundant and have shown that oxidants, as well as accumulation of metabolic byproducts, play major roles in IR. The isolated perfused heart model has been used very successfully in the past, allowing examination of IR, as well as the application of agents to combat IR injury. However, in the last few years there has been increased interest in a newly discovered component of IR. Apoptosis has recently been determined to occur in the post ischemic heart in vivo by this laboratory, as well as others. It remains unknown whether active cell death contributes to the decrease in myocardial performance characteristic of IR, however, the manipulation of apoptosis using various agents has been successfully documented in many different systems, including cardiac myocytes. Therefore, we sought to determine for the first time if: (1) Apoptosis occurs in the isolated buffer perfused heart and (2) If manipulation of apoptosis would protect against IR injury. (Abstract shortened by UMI.)

The goal of this work was to initiate a systematic investigation of the possible substrates for muscle glyconeogenesis under physiological circumstances--during recovery from prolonged submaximal exercise. The hypothesis was that amino acids mobilized from possibly increased body protein breakdown (in particular muscle protein degradation), or glycerol liberated from catabolism of body fat (especially intramuscular fat) during and after exercise might serve as substrates for muscle glyconeogenesis after exercise. In order to assess whole body protein breakdown, muscle myofibrillar protein degradation during and after exercise as well as to determine the incorporation of putative substrates into muscle glycogen during postexercise recovery, twelve-hour-fasted rats were infused intravenously with: (a) $\sp $C-U-urea, (b) $\sp $C-U-threonine (a representative of gluconeogenic amino acids) and $\sp3$H-6-glucose, and (c) $\sp $C-U-glycerol and $\sp3$H-6-glucose throughout two-hour basal, four-hour swim (or rest) and three-hour postexercise recovery periods. Arterial blood samples were taken every hour. Soleus, white and red gastrocnemius muscles were excised and assessed for 3-methylhistidine (3-MH) and tyrosine contents as well as for total and radiolabelled glycogen contents at the end of the postexercise recovery. The results indicate that: (1) whole body protein breakdown and muscle myofibrillar protein degradation increase significantly during and after prolonged swimming in white and red gastrocnemii as evidenced by an increased rate of urea production and increased 3-MH level in blood and in these muscles, respectively; (2) glyconeogenic amino acids released from increased body proteolysis appear to serve as substrates for glyconeogenesis after exercise in at least red gastrocnemius muscle, as demonstrated by the fact that nearly 11% of the label arising from $\sp $C-U-threonine and incorporated into muscle glycogen could be accounted for by muscle glyconeogenesis; and (3) circulating glycerol does not play a role in muscle glyconeogenesis. (Abstract shortened by UMI.)

The objective of this investigation was to compare the sensitivity of the intra-cranial and intra-muscular routes of inoculation of street rabies virus. This was done by determining the time of appearance of Negri bodies and/or infectivity in the brain and salivary glands of experimentally infected Swiss white mice, individual groups of five mice inoculated by either of these routes were sacrificed at daily intervals until they died of the infection. Brain and salivary glands from each mouse were examined by three methods: (a) standard impression smear technique, (b) mouse infectivity test, and (c) flourescent antibody technique. When obtainable, saliva samples were also examined by the mouse invectivity test. Out of 60 mice injected by the intra-cranial route, 38 showed Negri bodies when brains were examined by the standard impression smear technique; in one mouse they were detected as early as the fifth post-inoculation day. The salivary glands failed to show Negrigenesis when examined by this method. The presence of infectivity was demonstrated in the brain of 43 mice and preceded by one day the appearance of Negri bodies. Only three mice were found to excrete virus in salivary glands: the first an the eighth, the second on the ninth and the third on the tenth post-inoculation day. Saliva from the second of these three mice proved infectious. Rabies viral antigen was revealed by the fluorescent antibody technique in the brain of all five mice sacrificed on the second post-inoculation day, in that of two of the five killed on the third post-inoculation day and in that of every mouse thereafter. This method, like the direct smear examination, did not detect evidence of infection in any of the salivary glands. The lower sensitivity of the intra-muscular route of injection was evidenced by the late appearance and the marked irregularity of both lesions and infectivity in the 125 mice thus inoculated. Only 19 developed Negrigenesis in the brain; the earliest by the 10th post-inoculation day. Thirty-three mouse brains proved to harbour virus by the mouse infectivity test. The appearance of infectivity did not precede that of Negri bodies in the brain tissue. Only four mice excreted virus in salivary glands. Two saliva samples exhibited infectivity. The fluorescent antibody technique detected rabies viral antigen in 16 Negri-positive and 20 Negri-negative brains, seven of the latter being also non-infective for mice. Four brains found to contain virus were missed by this technique, although three of the fur disclosed Negrigenesis. Positive results were obtained by the fluorescent antibody technique with all mouse-infective salivary glands. Among field brain specimens from 100 domestic and wild animals, 11 revealed evidence of infection by the standard impression smear technique, 54 by the mouse infectivity test and 50 by the fluorescent antibody technique. The results of these studies indicate that the intra-cranial route of inoculation ins more sensitive than the intra-muscular one for the rapid detection of street rabies virus infection in Swiss white mice. Brain also proved to be the most satisfactory tissue for this purpose. Of the methods employed, the standard impression smear technique was found the least sensitive. In contrast to what was observed in experimental mice, the mouse infectivity test appeared more sensitive than the fluorescent antibody technique for the examination of field brain specimens.

The study of the metabolism of ethyl alcohol in rats expoxsed to a cold environment was investigated by means of uniformly 14C-labeled ethyl alcohol. In rats exposed to cold for five days, the rate of metabolism of alcohol was accelerated, in contrast to their controls kept at room temperature. Moreover, the rate of absorption of alcohol from the site of its administration and the rate of its removal from the blood was greater in cold-exposed animals than in rats maintained at room temperature. The observed increase in the rate of metabolism of alcohol in cold-exposed rats, however, was not proportional to the rate of increase in the general metabolism. In cold-acclimated rats, whether or not pre-treated with alcohol, cold exposure resulted in an increased rate of alcohol metabolism. In cold-acclimated alcohol pre-treated rats, the increase in the rate of alcohol metabolism was proportional to the increase in overall metabolism. The data also indicate that the rate of alcohol metabolism is essentially independent when given in various doses. However, a dose dependence on the ratio of oxidation of alcohol to the total foodstuff utilization was demonstrated. No detectable changes in the alcohol oxidation rate were caused by partial hepatectomy. A single dose of an adrenergic blocking agent, phenoxybenzamine, immediately prior to the introduction of alcohol, produced a decrease in the oxidation rate of alcohol in rats exposed to cold. This reduction was more pronounced when cold-exposed rats were pre-treated with phenoxybenzamine from the onset of cold exposure, i.e. for five days prior to alcohol administration. The positive influence of the thyroid gland on the metabolic rate of alcohol in animals exposed to cold was demonstrated by blocking hormone production with potassium perchlorate during the cold conditioning period.

An enigma has existed since 1948 concerning the possible interrelationship of vitamin A and vitamin C. We first examined this possible relationship by taking advantage of the known effects of cold on tissue ascorbic acid. We found that vitamin A deficient rats had a decreased resistance to cold and that prior to becoming moribund, their vitamin C status was unaffected by the deficiency. The administration of vitamin C during the terminal stages of vitamin A deficiency did not alleviate the signs of vitamin A deficiency nor prolong survival in the cold. The data of the above experiments called our attention to the importance and necessity of utilizing the pair-feeding technique and a vitamin A deficient test diet of a different composition. We found that the onset of vitamin A deficiency at room temperature occurred ten days earlier on a yeast-free vitamin A deficient test diet. In addition, the control animals on the new diet had a distinct tendency for a better weight gain, a smaller liver and an increased liver storage of vitamin A. Exogenous vitamin C administered from the onset of the experiment did not retard nor ameliorate the course of the deficiency or the survival of rats fed either the U.S.P. or a yeast-free vitamin A deficient test diet. Administered vitamin C was readily taken up by the liver of rats on the yeast-free test diet but not by the liver of rats on the U.S.P. yeast-containing vitamin A deficient test diet. We believe this difference in composition of the test diets explains why a number of investigators were unable to find modifications in the ascorbic acid status of their animals after treatment with vitamin C. Pair-feeding adequately accounted for the decrease in liver reduced ascorbic acid which occurred in terminal vitamin A deficiency. Evidently, no relationship exists between the rat's resources of vitamin A and its capacity to synthesize ascorbic acid. Reduced glutathione does not seem to be the yeast factor which prevents the liver uptake of exogenous vitamin C. But, the administered reduced glutathione enhanced liver storage of vitamin A in normal rats and hastened the onset of the body weight gain plateau of vitamin A deficient rats by approximately five days. Guinea pig experiments demonstrated that treatment with moderate amounts of vitamin A did not hasten nor retard the development of scurvy. In addition, it was found that the absence of liver vitamin A in the guinea pig had no effect on the uptake and storage of supplemented vitamin C. Investigation into the beneficial effect of a high fat diet in the cold and the role of vitamins A and C revealed that increased fat in the diet exerts distinct beneficial effects in the cold, which are not enhanced when the diet is eaten in excess. We believe the mechanisms by which fat becomes a superior dietary constituent, are probably brought about by a conservation of energy resulting from a decrease in active lipogenesis and a decrease in specific dynamic action of non-fat foodstuffs. Fat promotes these decreases directly and also promotes an increased efficiency of the intestinal tract. The resultant energy conserved becomes available for heat production. In the cold, indications were found supporting the hypothesis that ascorbic acid may be intimately associated with some phase of fat metabolism. The requirement of vitamin A in the cold was noticeably increased on the high fat diet.

The ribosomes of Vibrio costicola were stable over a wide range of salt concentrations. Sucrose gradient profiles of ribosomes from cells grown in different salt concentrations and isolated in various salt concentrations were similar. The sedimentation coefficients of the ribosomal particles were 64, 48, and 28 S for the monosome, large subunit, and small subunit, respectively. These values were not altered by the NaCl concentration of the growth medium nor by the salt concentration of the isolation buffer. There was, however, slight evidence that higher salt concentrations were removing some of the ribosomal proteins. The total ribosomal proteins were found to be more acidic (B/A = 1.08) than the total ribosomal proteins of E. coli (B/A = 1.58) but less acidic than the total ribosomal proteins of H. cutirubrum (B/A = 0.69). The relative acidity of the total ribosomal proteins was not changed by the NaCl concentration the growth medium. Two ribosomal proteins equivalent to the E. coli S1 and L7/12 were purified and the partial amino acid sequence of the latter was determined. The V. costicola protein was 79% homologous with the E. coli protein and 74% homologous with an equivalent protein from the unclassified moderate halophile, H.x. The average hydrophobicity of the V. costicola total and purified ribosomal proteins were not significantly different than those of E. coli. An in vitro protein synthesizing system was developed for V. costicola. The in vitro system was energy dependent and sensitive to inhibitors of protein synthesis. The poly-uridylic acid dependent system incorporated phenylalanine into oligophenylalanines. The in vitro system directed by poly-U had a salt optimum of 0.15 M with greater activity in NH4Cl than KCl which had greater activity than NaCl. The magnesium optimum was approximately 18 mM. The in vitro system directed by "endogenous" messenger had similar salt response as the poly-U system except that NaCl was inhibitory at all concentrations. Increasing the salt concentration above the optimum increased the misreading of the poly-U message. The in vitro protein synthesizing system was stable for at least 8 hours in 1.0 M NaCl, KCl, or NH4Cl. The ribosomes and protein synthesizing system demonstrated considerable salt stability. The low salt optimum of the protein synthesis system and previously studied V. costicola enzymes and the effects of salts on misreading of poly-U suggest that the distribution of ions measured as intracellular may not be uniform throughout the cell. The envelope of the cell may bind large amounts of these ions leaving the cytoplasm with a relatively low "free" ion concentration.